Proximity sensor device

ABSTRACT

Proximity sensor devices are described that integrate a light emitting diode with a light sensor assembly in a single, compact package. The proximity sensor devices comprise a lead frame having a surface. The light emitting diode and light sensor assembly are mounted to the lead frame proximate to the surface. The light emitting diode is configured to emit electromagnetic radiation in a limited spectrum of wavelengths, while the light sensor assembly is configured to detect electromagnetic radiation in the limited spectrum of wavelengths emitted by the light emitting diode. An encapsulation layer is formed on the surface over the light emitting diode and light sensor assembly. A trench is formed in the encapsulation layer to receive electromagnetic radiation blocking material configured to block electromagnetic radiation in the limited spectrum of wavelengths to at least partially mitigate crosstalk between the light emitting diode and the light sensor assembly.

BACKGROUND

Electronic devices, such as smart phones, tablet computers, digitalmedia players, and so forth, increasingly employ optical proximitysensors to detect nearby objects without any physical contact betweenthe object and the device. In this manner, proximity sensors may be usedto control the manipulation of a variety of functions provided by suchdevices. For example, an electronic device such as a smart phone may usea proximity sensor to detect when the device is held near the face andear of its user to deactivate the display and touchscreen of the device.This allows the device to conserve battery power and prevent inadvertentinputs from the user's face and ear. Optical proximity sensors typicallyinclude a light emitting diode (LED) that emits electromagneticradiation in a limited spectrum of wavelengths (e.g., infrared (IR))that are reflected by objects near the proximity sensor. A light sensorreceives the reflected electromagnetic radiation which is converted toan electrical signal (e.g., a current or voltage) indicative of thepresence of an object. In some instances, the light sensor may alsofunction as an ambient light sensor to control the brightness of thedevice's display based upon the surrounding ambient light environment.

SUMMARY

Proximity sensor devices are described that integrate a light emittingdiode and a light sensor assembly in a single, compact package. In oneor more implementations, the proximity sensor devices may comprise alead frame having a surface. The light emitting diode and light sensorassembly are mounted to the lead frame proximate to the surface. Thelight emitting diode is configured to emit electromagnetic radiation ina limited spectrum of wavelengths (e.g., infrared (IR)), while the lightsensor assembly is configured to detect electromagnetic radiation in abroad spectrum of wavelengths, including the limited spectrum ofwavelengths emitted by the light emitting diode (e.g., infrared (IR)),visible light, and so on. An encapsulation layer is provided on thesurface over the light emitting diode and light sensor assembly. Theencapsulation layer includes a trench formed therein to receiveelectromagnetic radiation blocking material configured to blockelectromagnetic radiation in the limited spectrum of wavelengths to atleast partially mitigate crosstalk between the light emitting diode andthe light sensor assembly.

This Summary is provided to introduce a selection of concepts in asimplified form that is further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used as an aid in determining the scope of the claimed subjectmatter.

DRAWINGS

The detailed description is described with reference to the accompanyingfigures. The use of the same reference numbers in different instances inthe description and the figures may indicate similar or identical items.

FIG. 1 is a diagrammatic top surface plan view illustrating a proximitysensor device in accordance with an example implementation of thepresent disclosure.

FIG. 2 is a diagrammatic cross-sectional side elevation viewillustrating the proximity sensor device of FIG. 1 taken along plane2-2.

FIG. 3 is a diagrammatic partial cross-sectional elevation viewillustrating the electronic device of FIG. 2 in an example environment,wherein the proximity sensor device is shown mounted within anelectronic device beneath a cover.

FIG. 4 is a diagrammatic top surface plan view illustrating a proximitysensor device in accordance with an example implementation of thepresent disclosure.

FIG. 5 is a diagrammatic cross-sectional side elevation viewillustrating the proximity sensor device of FIG. 4 taken along plane5-5.

FIG. 6 is a diagrammatic partial cross-sectional elevation viewillustrating the electronic device of FIG. 5 in an example environment,wherein the proximity sensor device is shown mounted within anelectronic device beneath a cover.

FIG. 7 is a diagrammatic top surface plan view illustrating a proximitysensor device in accordance with an example implementation of thepresent disclosure.

FIG. 8 is a diagrammatic cross-sectional side elevation viewillustrating the proximity sensor device of FIG. 7 taken along plane8-8.

FIG. 9 is a diagrammatic partial cross-sectional elevation viewillustrating the electronic device of FIG. 8 in an example environment,wherein the proximity sensor device is shown mounted within anelectronic device beneath a cover.

FIG. 10 is a diagrammatic top surface plan view illustrating a proximitysensor device in accordance with an example implementation of thepresent disclosure.

FIG. 11 is a diagrammatic cross-sectional side elevation viewillustrating the proximity sensor device of FIG. 10 taken along plane11-11.

FIG. 12 is a diagrammatic top surface plan view illustrating a proximitysensor device in accordance with an example implementation of thepresent disclosure.

FIG. 13 is a diagrammatic cross-sectional side elevation viewillustrating the proximity sensor device of FIG. 10 taken along plane13-13.

FIG. 14 is a diagrammatic partial cross-sectional elevation viewillustrating the electronic device of FIG. 12 in an example environment,wherein the proximity sensor device is shown mounted within anelectronic device beneath a cover.

FIG. 15 is a flow diagram illustrating a process in an exampleimplementation for fabricating proximity sensor devices in accordancewith the present disclosure, such as the proximity sensor devices shownin FIGS. 1 through 14.

DETAILED DESCRIPTION Overview

Proximity sensors used in electronic devices may employ discrete lightemitting diodes (e.g., an infrared light emitting diode (IR-LED)) andlight sensor assemblies (e.g., an IR light sensor, an integratedIR/ambient light sensor, etc.) that are separately packaged and mountedto a printed circuit board (PCB) of the device. This arrangementrequires a relatively large amount of space on the printed circuitboard. Moreover, to mitigate cross-talk between the light emitting diodeand the light sensor assembly, a physical barrier may be formed in theglass cover over the proximity sensor between the component packages.This physical barrier increases the amount of printed circuit boardspace used by the proximity sensor.

Consequently, proximity sensors were developed that integrate the lightemitting diode and the light sensor assembly into single integratedpackages that are mounted to the printed circuit board. In one example,the integrated packages utilize a conventional lead frame that includesdual pre-molded cavities for the light emitting diode and light sensorassembly. In other examples, the integrated packages are fabricatedusing organic laminated substrates or a printed circuit board with ametal cap. However, these integrated packages have large form factorsdue to constraints imposed by conventional packaging technologies. Forexample, the pre-molding process used with conventional lead framesrequires relatively tall and wide cavity walls for mechanical strengthand robustness. Similarly, integrated packages fabricated from organiclaminated substrates or using a printed circuit board and metal cap tendto have an undesirably high profile or thickness. None of the integratedpackages facilitate mounting of a physical barrier to mitigatecross-talk between the light emitting diode and light sensor assembly.

Accordingly, techniques are described for fabricating proximity sensordevices that integrate a light emitting diode (e.g., an infrared lightemitting diode (IR-LED)) and a light sensor assembly (e.g., an IR lightsensor, an integrated IR/ambient light sensor, etc.) in a single,compact package. The proximity sensor devices may comprise a packagethat employs an encapsulated lead frame. A light emitting diodeconfigured to emit electromagnetic radiation in a limited spectrum ofwavelengths (e.g., infrared (IR)) is mounted to the lead frame proximateto the surface of the lead frame. For example, the light emitting diodemay be mounted within a reflector formed in the surface of the leadframe to collimate the electromagnetic radiation emitted by the lightemitting diode. A light sensor assembly is mounted to the lead frame onthe surface. The light sensor assembly is configured to detectelectromagnetic radiation in a broad spectrum of wavelengths. Anencapsulation layer is formed on the surface over the light emittingdiode and light sensor assembly. The encapsulation layer includes atrench formed therein to receive electromagnetic radiation blockingmaterial configured to block electromagnetic radiation in the limitedspectrum of wavelengths emitted by the light emitting diode to at leastpartially mitigate crosstalk between the light emitting diode and thelight sensor assembly. In one or more implementations, the encapsulationlayer further includes a second trench formed therein between the firsttrench and the light sensor assembly. The second trench is configured toreceive an electromagnetic radiation barrier operable to blockelectromagnetic radiation in a limited spectrum of wavelengths tofurther mitigate crosstalk between the light emitting diode and thelight sensor assembly. In a possible embodiment, two trenches can becombined to have one large trench filled with radiation blockingmaterial and a central cut to serve dual function.

Example Implementations

FIGS. 1 through 14 illustrate proximity sensor devices 100 in accordancewith example implementations of the present disclosure. As shown, theproximity sensor devices 100 comprise integrated packages that include alead frame 102. The lead frame 102 functions to furnish mechanicalsupport to the components of proximity sensor device 100 and provideelectronic interconnectivity to the proximity sensor device 100 (e.g.,provide interconnectivity between other electronic components and theproximity sensor device 100, and so forth). In one or moreimplementations, the integrated package may comprise a flat no leadspackage such as a QFN (Quad Flat No leads) package, a DFN (Dual Flat Noleads) package, or the like. The lead frame 102 may be comprised of acopper lead frame, or the like. However, other lead frame structures arepossible.

One or more light emitting diodes (a single light emitting diode 104 isillustrated) are mounted near a surface 106 of the lead frame 102. Thelight emitting diode 104 is configured to emit electromagnetic radiationin a limited spectrum of wavelengths. For example, the light emittingdiode 104 may be an infrared light emitting diode (IR-LED) configured toemit electromagnetic radiation in the infrared light spectrum. Theinfrared light spectrum (infrared light) includes electromagneticradiation that ranges in wavelength from approximately seven hundred(700) nanometers to approximately three hundred thousand (300,000)nanometers. The light emitting diode 104 may also be configured to emitelectromagnetic radiation in a known, predetermined pattern (e.g., emitsa square wave of known width and frequency for a predetermined time).

The light emitting diode 104 may be positioned in a reflector 108 tocollimate the electromagnetic radiation emitted from the light emittingdiode 104, which increases the peak power of the emitted electromagneticradiation. As illustrated, the reflector 108 may be formed as a dish 110recessed in the surface 106 of the lead frame 102 so that the lightemitting diode 104 is positioned at least partially below the surface106, reducing the height of the package. In one or more implementations,the reflector 108 may be etched into the surface 106 of the lead frame102 via suitable etching techniques. However, it is contemplated thatother fabrication techniques may be used. The reflector 108 may furtherbe coated with a material or materials that reflect, or at leastpartially reflect, electromagnetic radiation within the spectrum emittedby the light emitting diode 104. For instance, where the light emittingdiode 104 comprises an IR-LED, the reflector 108 may be coated withmaterials that reflect electromagnetic radiation occurring in theinfrared light spectrum. Example materials include, but are not limitedto: nickel, silver, aluminum plating, or the like.

In one or more implementations, the reflector 108 may comprise aparabolic reflector. Thus, the recessed dish 110 may be formed to havean at least substantially parabolic cross-section. However, it iscontemplated that the reflector 108 may have a variety of shapes (e.g.spherical, elliptical, faceted, etc.) depending on design requirements.Further, it is contemplated that the light emitting diode 104 may bemounted to the surface 106 of the lead frame 102 without a reflector108.

A light sensor assembly 112 is mounted proximate to the surface 106 ofthe lead frame 102 opposite the light emitting diode 104. The lightsensor assembly 112 is configured to detect electromagnetic radiation inthe spectrum of wavelengths emitted by the light emitting diode 104 thatis reflected off an object in close proximity to the proximity sensordevice 100. For instance, where the light emitting diode 104 comprisesan IR-LED, the light sensor assembly 112 may be configured to detectelectromagnetic radiation within the infrared light spectrum. Inimplementations, the light sensor assembly may employ photodetectorssuch as photodiodes, phototransistors, or the like, that convertreceived electromagnetic radiation in the limited spectrum ofwavelengths emitted by the light emitting diode 104 (e.g., infrared)into an electrical signal (e.g., a current or voltage).

The light sensor assembly 112 may further be configured to detect theambient light environment surrounding the proximity sensor device 100.For example, the light sensor assembly 112 may detect electromagneticradiation occurring in the visible light spectrum (e.g., electromagneticradiation having a wavelength ranging from approximately three hundredand ninety (390) nanometers to approximately seven hundred and fifty(750) nanometers) incident on the light sensor assembly 112. Thus, thelight sensor assembly 112 may be configured to detect electromagneticradiation occurring in both the infrared light spectrum and the visiblelight spectrum that is incident on the light sensor assembly 112. It iscontemplated that the light sensor assembly 112 may also detectelectromagnetic radiation emitted from a nearby object (e.g., anotherelectronic device with an IR transmitter).

An encapsulation layer 114 is provided on the surface 106 of the leadframe 102 over the light emitting diode 104 and the light sensorassembly 112. The encapsulation layer 114 is formed of a material thatis at least substantially transparent to electromagnetic radiationwithin the limited spectrum of wavelengths emitted by the light emittingdiode 104 and/or received by the light sensor assembly 112 (e.g.,infrared). In this manner, electromagnetic radiation emitted by thelight emitting diode 104 and/or reflected from an object in proximity tothe proximity sensor device 100 may pass through the encapsulation layer114. In one or more implementations, the encapsulation layer 114 isfabricated of a transparent epoxy material that allows at leastapproximately ninety (90) percent of the electromagnetic radiationincident on the encapsulation layer 114 to pass through the layer 114.However, other transparent materials (e.g., glass) may be used.Moreover, it is contemplated that the encapsulation layer 114 could befabricated of materials that are translucent or opaque and provided withtransparent windows for the light emitting diode 104 and light sensorassembly 112.

A trench 116 is provided in the encapsulation layer 114 between thelight emitting diode 104 and the light sensor assembly 112. The trench116 is at least partially filled with electromagnetic radiation blockingmaterial 118 configured to block (e.g., to reflect and/or absorb)electromagnetic radiation at least within the limited spectrum ofwavelengths emitted by the light emitting diode 104. As shown, thetrench 116 may be formed so that it extends completely through theencapsulation layer 114 (e.g., the depth of the trench 116 is at leastequal to the thickness of the encapsulation layer 114). In this manner,the electromagnetic radiation blocking material 118 may extend from atleast the surface 106 of the lead frame 102 to an outer surface 140 ofthe encapsulation layer 114. However, it is contemplated that the trench116 may extend past the surface 106 of the lead frame 102 and into thelead frame 102, so that the electromagnetic radiation blocking material118 extends below the surface 106 of the lead frame 102. It is alsocontemplated that, in one or more implementations, the trench 116 mayextend only partially through the encapsulation layer 114 (e.g., doesnot extend to the surface 106 of the lead frame 102). In suchimplementations, the electromagnetic radiation blocking material 118would also not extend to the surface 106 of the lead frame 102.

The trench 116 may have adequate width to hold an amount (e.g.,thickness) of electromagnetic radiation blocking material 118 that issufficient to effectively block electromagnetic radiation from the lightemitting diode 104 within the encapsulation layer 114 within the sizeconstraints of the lead frame 102. Thus, it will be appreciated that thedepth and the width of trench 116 will depend on the particulardesign/performance requirements of the proximity sensor device 100(e.g., the characteristics (size, power, sensitivity, etc.) of the lightemitting diode 104 and light sensor assembly 112, the size of the leadframe 102, the thickness of the encapsulation layer 114, theencapsulation layer 114 material, the electromagnetic radiation blockingmaterial 118 selected, and so forth).

In implementations, as illustrated in FIGS. 2, 3, 5, and 6, the lightemitting diode 104 is positioned in the reflector 108, which allows thetopmost surface point 122 of the light emitting diode 104 to be belowthe bottommost point 124 of the trench 116. The position of the trench116 (and electromagnetic radiation blocking material 118) along thesurface 106 of the lead frame 102 (e.g., between the light emittingdiode 104 and the light sensor assembly 112) may be selected based onthe particular design/performance requirements of the proximity sensordevice 100 and/or the fabrication techniques employed. In theimplementations shown in FIGS. 1 through 6, the trench 116 isillustrated as being positioned approximately in the middle of the leadframe 102 between the light emitting diode 104 and the light sensorassembly 112. However, it is contemplated that the position of trench116 may vary. For example, in one or more implementations, the trench116 may be formed closer to light emitting diode 104 and farther fromlight sensor assembly 112. In other implementations, the trench 116 maybe formed closer to light sensor assembly 112 and farther from lightemitting diode 104.

The electromagnetic radiation blocking material 118 may be configured ina variety of ways. For example, in the implementation shown in FIGS. 1through 3, the electromagnetic radiation blocking material 118 may fillthe trench 116 so that the top surface 120 of the material 118 is atleast approximately flush (level) with the outer surface 140 of theencapsulation layer. In another implementation, shown in FIGS. 4 through6, the electromagnetic radiation blocking material 118 may extend beyondthe outer surface 140 of the encapsulation layer 114 so that the topsurface 120 of the electromagnetic radiation blocking material 118 isabove the surface 140. However, it is also contemplated that in someimplementations, it may be unnecessary for the electromagnetic blockingmaterial 118 to completely fill the trench 116. Thus, the top surface120 of the electromagnetic radiation blocking material 118 may be belowthe outer surface 140 of the encapsulation layer 114.

As noted, the electromagnetic radiation blocking material 118 maycomprise a material that blocks (e.g., reflects and/or absorbs)electromagnetic radiation at least within the limited spectrum ofwavelengths emitted by the light emitting diode 104. For example, inimplementations where the light emitting diode 104 comprises a IR-LED,the electromagnetic radiation blocking material 118 may comprise amaterial that is capable of at least substantially blocking (e.g.,reflecting and/or absorbing) electromagnetic radiation within theinfrared spectrum. However, it is contemplated that both electromagneticradiation in the visible light spectrum and the infrared light spectrummay be blocked by the electromagnetic radiation blocking material 118.In one example, the electromagnetic radiation blocking material 118 maybe comprised of an electromagnetic radiation blocking epoxy material,such as an infrared light blocking epoxy material. In another example,the electromagnetic radiation blocking material 118 may comprise aresilient material such as silicone. Other examples are possible.

As illustrated in FIGS. 7 through 9, the proximity sensor device 100 mayfurther include a second trench 126 provided in the encapsulation layer114 between the first trench (trench 116) and the light sensor assembly112. Thus, as shown, the first trench 116 is positioned proximate to thelight emitting diode 104, and the second trench 126 is positionedproximate to the light sensor assembly 112. The second trench 126 isconfigured to receive an electromagnetic radiation barrier 128 operableto block electromagnetic radiation in the spectrum of wavelengthsemitted by the light emitting diode 104 to further mitigate crosstalkbetween the light emitting diode 104 and the light sensor assembly 112.

The second trench 126 may be formed so that it extends completelythrough the encapsulation layer 114 (e.g., the depth of the secondtrench 126 is at least equal to the thickness of the encapsulation layer114). However, like the first trench 116, it is contemplated that thesecond trench 126 may extend past the surface 106 of the lead frame 102and into the lead frame 102, so that the electromagnetic radiationbarrier 128 may extend below the surface 106 of the lead frame 102. Itis also contemplated that, in one or more implementations, the secondtrench 126 may extend only partially through the encapsulation layer 114(e.g., does not extend to the surface 106 of the lead frame 102). Insuch implementations, the electromagnetic radiation barrier 128 wouldalso not extend to the surface 106 of the lead frame 102. Moreover, thesecond trench 126 may have a width that is adequate to receive theelectromagnetic radiation barrier 128 within the size constraints of thelead frame 102.

The electromagnetic radiation barrier 128 may comprise a material thatblocks (e.g., reflects and/or absorbs) electromagnetic radiation atleast within the limited spectrum of wavelengths emitted by the lightemitting diode 104. For example, in implementations where the lightemitting diode 104 comprises an IR-LED, the electromagnetic radiationbarrier 118 may comprise a material that is capable of at leastsubstantially blocking (e.g., reflecting and/or absorbing)electromagnetic radiation within the infrared spectrum. However, it iscontemplated that both electromagnetic radiation in the visible lightspectrum and the infrared light spectrum may be blocked by theelectromagnetic radiation barrier 128. In one example, theelectromagnetic radiation barrier 128 may be fabricated of glass ofdiffering refractive indices. However, other materials may be used.

In various implementations, the proximity sensor devices 100 areconfigured to be integrated within an electronic device to furnishproximity detection functionality to the device. As illustrated in FIGS.3, 6, and 9, the proximity sensor device 100 may be positioned adjacentto a cover 130 of the device so that the cover 130 extends over at leasta portion of the proximity sensor device 100. The cover 130 may befabricated of a material that is at least substantially opaque (e.g.,opaque glass) to electromagnetic radiation within the limited spectrumof wavelengths emitted by the light emitting diode 104 (e.g., infrared).As shown, optical windows 136 are provided in the cover 130 over thelight emitting diode 104 and the light sensor assembly, respectively.The optical windows 136 may be at least substantially transparent (e.g.,transparent glass) with a low refractive index to electromagneticradiation within the limited spectrum of wavelengths emitted by thelight emitting diode 104 (e.g., infrared). In this manner, the opticalwindows 136 are configured to allow electromagnetic radiation from thelight emitting diode 104 and/or reflected from an object (target) topass there through.

In the implementations illustrated in FIGS. 3 and 6, the proximitysensor device 100 is shown mounted (e.g., to a printed circuit board)immediately adjacent to the cover 130 so that the top surface 120 of theelectromagnetic radiation blocking material 118 at least substantiallyabuts the cover 130 within an opaque area of the cover 130. Forinstance, in the implementation shown in FIGS. 1 through 3, theproximity sensor device 100 is mounted against the cover 130 so that theouter surface 140 of the encapsulation layer 114 rests against an innersurface of the cover 130. In this configuration, the top surface 120 ofthe electromagnetic radiation blocking material 118, which is flush withthe outer surface 140 of the encapsulation layer 114, abuts the cover130. Similarly, in the implementation shown in FIGS. 4 through 6, theproximity sensor device 100 is mounted adjacent to, but spaced awayfrom, the cover 130 so that a thin gap is provided between the outersurface 140 of the encapsulation layer 114 and the inner surface of thecover 130. The electromagnetic radiation blocking material 118 extendsbeyond the outer surface 140 of the encapsulation layer 114 by a lengththat is at least equal to or greater than the thickness of the gap sothat the top surface 120 of the electromagnetic radiation blockingmaterial 118 abuts the cover 130. In this implementation, a resilientelectromagnetic radiation blocking material 118 may be employed,allowing the material 118 to be compressed by the cover 130 to eliminateor reduce spaces between the material 118 and the inner surface of thecover 130.

In the implementation illustrated in FIG. 9, the proximity sensor device100 is mounted so that space is provided between the device 100 and thecover 130 to accommodate the electromagnetic radiation barrier 128. Asnoted, the electromagnetic radiation barrier 128 is configured tofurther mitigate crosstalk due to electromagnetic radiation emitted bythe light emitting diode 104 that is reflected from the cover 130 (seeFIG. 9). The electromagnetic radiation barrier 128 may be integral withthe cover 130, or may be a separate component that abuts the cover 130along its top surface 132. The electromagnetic radiation barrier 128 maybe attached to the cover via an adhesive.

In one or more implementations, the lead frame 102 of the proximitysensor device 100 may include a tab 142. As illustrated in FIGS. 10 and11, the tab 142 extends beneath the trench 116 to preventelectromagnetic radiation from entering the substrate 144 (e.g., body)of the lead frame 102 and passing beneath the electromagnetic radiationblocking material 118. As illustrated in FIG. 11, the tab 142 isintegral with the surface 106 of the lead frame 102. Thus, inimplementations, the light sensor assembly 112 may be mounted over thetab 142. The tab 142 may be formed of a suitable material such as ametal (e.g., aluminum), or the like.

In the implementation illustrated in FIGS. 12 through 14, the proximitysensor device 100 is shown with a widened trench 146. Like the trenches116 illustrated above, the widened trench 146 is at least partiallyfilled with electromagnetic radiation blocking material 118, and may beformed so that it extends completely through the encapsulation layer114. In this manner, the electromagnetic radiation blocking material 118may extend from at least the surface 106 of the lead frame 102 to anouter surface 140 of the encapsulation layer 114. Similarly, as with thetrenches 116 illustrated above, it is contemplated that the widenedtrench 146 may extend past the surface 106 of the lead frame 102 andinto the lead frame 102 so that the electromagnetic radiation blockingmaterial 118 extends below the surface 106 of the lead frame 102. It isalso contemplated that, in one or more implementations, the trench 146may extend only partially through the encapsulation layer 114 (e.g.,does not extend to the surface 106 of the lead frame 102). In suchimplementations, the electromagnetic radiation blocking material 118would also not extend to the surface 106 of the lead frame 102.

As shown in FIG. 14, the electromagnetic radiation blocking material 118is configured to receive the electromagnetic radiation barrier 128. Forinstance, the electromagnetic radiation blocking material 118 may beprovided with a recessed area 148 formed in the electromagneticradiation blocking material 118 (e.g., via a sawing process, an etchingprocess, a molding process, or the like). The electromagnetic radiationbarrier 128 may then be received in the recessed area 148 so that itslower edge is at least substantially surrounded by electromagneticradiation blocking material 118.

The widened trench 146 may have adequate width to hold an amount (e.g.,thickness) of electromagnetic radiation blocking material 118 that issufficient to effectively block electromagnetic radiation from the lightemitting diode 104 within the encapsulation layer 114 within the sizeconstraints of the lead frame 102. Moreover, the trench 146 may haveadequate width to allow for formation of the recessed area 148 in theelectromagnetic radiation blocking material 118 to receive theelectromagnetic radiation barrier 128. Thus, it will be appreciated thatthe depth and the width of trench 146 will depend on the particulardesign/performance requirements of the proximity sensor device 100(e.g., the characteristics (size, power, sensitivity, etc.) of the lightemitting diode 104 and light sensor assembly 112, the size of the leadframe 102, the thickness of the encapsulation layer 114, theencapsulation layer 114 material, the electromagnetic radiation blockingmaterial 118 selected, the size of the electromagnetic radiation barrier128, and so forth).

As noted, the proximity sensor device 100 may employ a flat no leadspackage such as a QFN (Quad Flat No leads) package, a DFN (Dual Flat Noleads) package, or the like. Thus, as illustrated in FIGS. 1, 4, and 7,the lead frame 102 may include one or more pads 138 that are configuredto provide electrical connectivity to the components residing on thelead frame 102 (e.g., the light emitting diode 104, the light sensorassembly 112, etc.) via a suitable connection technique such as wirebonding, or the like. However, other configurations are possible.

As noted, the proximity sensor devices 100 described above areconfigured to be integrated within an electronic device to furnishproximity detection functionality to the device. It is contemplated thata wide variety of electronic devices may employ proximity sensor devices100 in accordance with the present disclosure. Examples include, but arenot limited to: televisions, portable computers, and mobile devices suchas smart phones, mobile phones, tablet computers, hand-held gamingconsoles, and so on. For instance, a smart phone manufacturer mayintegrate a proximity sensor device 100 into a smart phone to provideproximity detection functionality to the smart phone. This allows thephone's processing system (e.g., a microprocessor, digital processor,etc.) to automatically control the manipulation of a variety offunctions provided by the smart phone when the phone is brought intoclose proximity with an object. For example, the smart phone may use theproximity sensor device 100 to detect the proximity of the phone to thehead of its user (e.g., during a telephone call). In this example, thelight emitting diode 104, an IR-LED, emits infrared light that isreflected off a portion of the ear and cheek of the user when the userholds the smart phone to his or her head. The reflected infrared lightis received by the light sensor assembly 112. In response, theprocessing system may power off the display and the touchscreen of thephone to prevent inadvertent input to the touchscreen by the user's earand cheek, and to conserve battery life. Moreover, the light sensorassembly 112 may be configured to sense the ambient light environmentsurrounding the electronic device (e.g., a smart phone, tablet computer,etc.). In this manner, the processing system of the device may beconfigured to automatically change the brightness, contrast, color, andso on of the display to provide an enhanced viewing experience to itsuser.

Example Fabrication Processes

FIG. 15 illustrates an example process 200 that employs flat no leadspackaging techniques to fabricate proximity sensors in accordance withthe present disclosure, such as the proximity sensors 100 shown in FIGS.1 through 14. In the process 200 illustrated, a light emitting diode ismounted proximate to a surface of a lead frame (Block 202). As noted,the light emitting diode may be configured to emit electromagneticradiation in a limited spectrum of wavelengths. For example, inimplementations, the light emitting diode may be comprised of aninfrared light emitting diode that is configured to emit electromagneticradiation in the infrared spectrum of wavelengths. The light emittingdiode may be fabricated utilizing appropriate semiconductor fabricationtechniques.

As described above, the light emitting diode may be contained in areflector. Thus, as shown in FIG. 15, a reflector may first be formed inthe surface of the lead frame using a suitable technique such asetching, or the like. The light emitting diode may then be mounted tothe lead frame within the reflector (Block 204). As shown in FIGS. 1through 14, the reflector may have a shape (e.g., parabolic, spherical,faceted, etc.) configured to collimate the electromagnetic radiationemitted from the light emitting diode to increase the peak power of theemitted electromagnetic radiation.

A light sensor assembly is mounted proximate to the surface of the leadframe (Block 206). As noted, the light sensor assembly is configured todetect the presence of nearby objects without any physical contact withthe object by detecting electromagnetic radiation in the limitedspectrum of wavelengths emitted by the light emitting diode that arereflected by a nearby object. The light sensor assembly may also beconfigured to detect the ambient light environment surrounding theproximity sensor device. Thus, in an implementation, the light sensorassembly may detect electromagnetic radiation occurring in the visiblelight spectrum and the infrared light spectrum incident on the lightsensor assembly. The light sensor assembly may be fabricated utilizingsuitable semiconductor fabrication techniques.

An encapsulation layer is next formed on the surface of the lead frame(Block 208) over the light emitting diode and the light sensor assembly.The encapsulation layer may comprise a plastic epoxy that is at leastsubstantially transparent to electromagnetic radiation within thelimited spectrum of wavelengths emitted by the light emitting diode. Forexample, in one or more implementations, the encapsulation layer mayallow at least about ninety (90) percent of the electromagneticradiation incident on the encapsulation layer to pass there through. Theencapsulation layer may be formed using a suitable molding process tomold the epoxy onto the surface of the lead frame. In one or moreimplementations, the encapsulation layer may also be formed over a tablayer (Block 210). The tab layer comprises a layer (e.g., aluminumplating, or the like) integrated with the lead frame of the proximitysensor device to prevent electromagnetic radiation from entering thesubstrate of the sensor device.

A trench is then formed in the encapsulation layer (Block 210) betweenthe light emitting diode and the light sensor assembly to receiveelectromagnetic radiation blocking material. In one or moreimplementations, a second trench may also be formed in the encapsulationlayer (Block 212) adjacent to the first trench. The second trench isconfigured to receive an electromagnetic radiation barrier as describedin the discussion of FIGS. 7 through 9. The trenches (e.g., the firsttrench, the second trench, the widened trench) may be formed in theencapsulation layer using a suitable sawing process. The use of a sawingprocess allows for precise control of the position, depth and width ofthe trenches. However, it is contemplated that other fabricationprocesses may be used to form the trenches. For example, the trenchesmay be formed using suitable molding processes. Other examples arepossible.

Electromagnetic radiation blocking material is then deposited in the(first) trench (Block 214). The electromagnetic radiation blockingmaterial is selected to block electromagnetic radiation in the limitedspectrum of wavelengths emitted by the light emitting diode. However, itis contemplated that the electromagnetic radiation blocking material mayalso block electromagnetic radiation having other wavelengths (e.g.,electromagnetic radiation in the visible light spectrum and the infraredlight spectrum may be blocked by the electromagnetic radiation blockingmaterial). In one example, the electromagnetic radiation blockingmaterial may comprise an electromagnetic radiation blocking epoxymaterial, such as an infrared light blocking epoxy material, howeverother materials, including resilient materials, may be used.

In one or more implementations, a widened trench may be formed in theencapsulation layer (Block 212). For example, where a sawing process isused to form the trench, a double trench may be cut into theencapsulation layer by causing multiple passes to be made by the saw.The electromagnetic radiation blocking material is then deposited in thewidened trench (Block 214). The electromagnetic radiation blockingmaterial may be configured to receive the electromagnetic radiationbarrier described in the discussion of FIGS. 12 through 14. For example,a suitable sawing process may be utilized to form a recessed area in theelectromagnetic radiation blocking material that is capable of receivingthe barrier. However, it is contemplated that other suitable techniques(e.g., etching, molding, etc.) may be utilized to form the recessedarea.

CONCLUSION

Although the subject matter has been described in language specific tostructural features and/or process operations, it is to be understoodthat the subject matter defined in the appended claims is notnecessarily limited to the specific features or acts described above.Rather, the specific features and acts described above are disclosed asexample forms of implementing the claims.

What is claimed is:
 1. A proximity sensor device comprising: a leadframe having a surface; a light emitting diode mounted to the lead frameproximate to the surface, the light emitting diode configured to emitelectromagnetic radiation in a limited spectrum of wavelengths; a lightsensor assembly mounted to the lead frame proximate to the surface, thelight sensor assembly configured to detect electromagnetic radiation inthe limited spectrum of wavelengths; and an encapsulation layer formedon the surface over the light emitting diode and light sensor assembly,the encapsulation layer including a trench formed therein to receiveelectromagnetic radiation blocking material, the electromagneticradiation blocking material configured to block electromagneticradiation in the limited spectrum of wavelengths to at least partiallymitigate crosstalk between the light emitting diode and the light sensorassembly.
 2. The proximity sensor device as recited in claim 1, whereinthe light emitting diode is mounted within a reflector formed in thesurface of the lead frame, the reflector configured to collimate theelectromagnetic radiation emitted by the light emitting diode.
 3. Theproximity sensor device as recited in claim 2, wherein the reflectorcomprises a parabolic reflector.
 4. The proximity sensor device asrecited in claim 1, wherein the trench is formed through theencapsulation layer, and wherein the electromagnetic radiation blockingmaterial extends from at least the surface of the lead frame to an outersurface of the encapsulation layer.
 5. The proximity sensor device asrecited in claim 1, wherein the light emitting diode comprises aninfrared light emitting diode configured to emit electromagneticradiation in the infrared light spectrum, and wherein the light sensorassembly comprises an infrared light sensor configured to detectelectromagnetic radiation in the infrared light spectrum.
 6. Theproximity sensor device as recited in claim 5, wherein theelectromagnetic radiation blocking material comprises an epoxy materialconfigured to block electromagnetic radiation in the infrared lightspectrum.
 7. The proximity sensor device as recited in claim 1, whereinthe encapsulation layer further includes a second trench formed thereinbetween the trench and the light sensor assembly, the second trenchconfigured to receive an electromagnetic radiation barrier operable toblock electromagnetic radiation in the limited spectrum of wavelengthsto further mitigate crosstalk between the light emitting diode and thelight sensor assembly.
 8. An proximity sensor device comprising: a leadframe having a surface; a light emitting diode mounted to the lead frameproximate to the surface, the light emitting diode configured to emitelectromagnetic radiation in a limited spectrum of wavelengths; a lightsensor assembly mounted to the lead frame proximate to the surface, thelight sensor assembly configured to detect electromagnetic radiation inthe limited spectrum of wavelengths; an encapsulation layer formed onthe surface over the light emitting diode and light sensor assembly, theencapsulation layer including a trench formed therein between the lightemitting diode and the light sensor assembly; and electromagneticradiation blocking material disposed within the trench, theelectromagnetic radiation blocking material configured to blockelectromagnetic radiation in the limited spectrum of wavelengths to atleast partially mitigate crosstalk between the light emitting diode andthe light sensor assembly.
 9. The proximity sensor device as recited inclaim 8, wherein the light emitting diode is mounted within a reflectorformed in the surface of the lead frame, the reflector configured tocollimate the electromagnetic radiation emitted by the light emittingdiode.
 10. The proximity sensor device as recited in claim 9, whereinthe reflector comprises a parabolic reflector.
 11. The proximity sensordevice as recited in claim 8, wherein the trench is formed through theencapsulation layer, and wherein the electromagnetic radiation blockingmaterial extends from at least the surface of the lead frame to an outersurface of the encapsulation layer.
 12. The proximity sensor device asrecited in claim 8, wherein the light emitting diode comprises aninfrared light emitting diode configured to emit electromagneticradiation in the infrared light spectrum, and wherein the light sensorassembly comprises an infrared light sensor configured to detectelectromagnetic radiation in the infrared light spectrum.
 13. Theproximity sensor device as recited in claim 12, wherein theelectromagnetic radiation blocking material comprises an epoxy materialconfigured to block electromagnetic radiation in the infrared lightspectrum.
 14. The proximity sensor device as recited in claim 8, whereinthe encapsulation layer further includes a second trench formed thereinbetween the trench and the light sensor assembly, the second trenchconfigured to receive an electromagnetic radiation barrier operable toblock electromagnetic radiation in the limited spectrum of wavelengthsto further mitigate crosstalk between the light emitting diode and thelight sensor assembly.
 15. A process comprising: mounting a lightemitting diode proximate to a surface of a lead frame, the lightemitting diode configured to emit electromagnetic radiation in a limitedspectrum of wavelengths; mounting a light sensor assembly proximate tothe surface of the lead frame, the light sensor assembly configured todetect electromagnetic radiation in the limited spectrum of wavelengths;providing an encapsulation layer on the surface of the lead frame overthe light emitting diode and the light sensor assembly, and forming atrench in the encapsulation layer between the light emitting diode andthe light sensor assembly to receive electromagnetic radiation blockingmaterial, the electromagnetic radiation blocking material configured toblock electromagnetic radiation in the limited spectrum of wavelengthsto at least partially mitigate crosstalk between the light emittingdiode and the light sensor assembly.
 16. The process as recited in claim15, wherein the mounting of the light emitting diode comprises etching areflector into the surface of the lead frame and mounting the lightemitting diode within the reflector, the reflector configured tocollimate the electromagnetic radiation emitted by the light emittingdiode.
 17. The process as recited in claim 16, wherein the reflectorcomprises a parabolic reflector.
 18. The process as recited in claim 15,further comprising depositing the electromagnetic radiation blockingmaterial within the trench.
 19. The process as recited in claim 18,wherein the trench is formed through the encapsulation layer, andwherein the electromagnetic radiation blocking material extends from atleast the surface of the lead frame to an outer surface of theencapsulation layer.
 20. The process as recited in claim 15, wherein thelight emitting diode comprises an infrared light emitting diodeconfigured to emit electromagnetic radiation in the infrared lightspectrum, and wherein the light sensor assembly comprises an infraredlight sensor configured to detect electromagnetic radiation in theinfrared light spectrum.
 21. The process as recited in claim 20, whereinthe electromagnetic radiation blocking material comprises an epoxymaterial configured to block electromagnetic radiation in the infraredlight spectrum.
 22. The process as recited in claim 15, furthercomprises forming an encapsulation layer further includes a secondtrench formed therein between the trench and the light sensor assembly,the second trench configured to receive an electromagnetic radiationbarrier operable to block electromagnetic radiation in the limitedspectrum of wavelengths to further mitigate crosstalk between the lightemitting diode and the light sensor assembly.